Selective call messaging, such as paging messaging, involves transmitting a message or a page to an intended selective call receiver by radio frequency (RF) signals. The page is received from an originator at a selective call terminal and is encoded into a format recognizable by the receiver. A selective call address assigned to the receiver is added to the message to indicate the intended receiver. The message is then transmitted for reception within a selective call system coverage area in which the receiver is expected to be located.
Conventionally, tone, voice, and numeric pages are received by the selective call terminal from remote devices via telephone audio modems or DTMF tone signalling. In addition, some pages are originated from information supplied to video display terminals (VDTs) coupled directly to the selective call terminal. The format of the signals received from the telephone and the VDTs are known to the selective call terminal and are compatible with the formatting of the selective call signals into known signalling formats such as POCSAG, a paging format developed by the Post Office Code Standardization Advisory Group. For example, numeric information from remote devices is typically received at the selective call terminal as DTMF tone information or alternatively information is received by the paging terminal in seven-bit ASCII format where each four-bit numeric character is represented by a seven-bit ASCII code and transmitted in POCSAG numeric four-bit message format.
With the advent of alphanumeric paging, the information received by selective call terminals is also received in seven-bit ASCII (American Standard Code Information Interchange) format and transmitted in seven-bit POCSAG alpha message format.
Yet, with the increase in alphanumeric paging which can originate from any of a number of input devices capable of coupling to a selective call terminal and with the advent of selective call receivers which can be data reception devices for computers, such as Personal Computers (PCs) or Laptop Computers, multiple data formats may be received by the selective call terminal which may or may not be compatible with the signalling format of the system, such as POCSAG. For example, there is no provision in POCSAG for transmitting eight-bit data or for conveying eight-bit binary data to a paging terminal. Also, the selective call receiver must necessarily be able to receive the signals in POCSAG or a known signalling format and reassemble the data of the message from the signalling format in which the message is received.
One solution would be to modify the selective call terminals to receive eight-bit information and encode this data in the POCSAG format. This solution, though, would be costly to the selective call service provider, as well as requiring down-time for the system to install.
An additional problem results from the form in which the information is received at the terminal. Alphanumeric information may be received by the terminal in standard seven-bit information transfer protocols, such as PET (Paging Entry Terminal protocol, sometimes called TAP for Telocator Alphanumeric Protocol) and TNPP (Telocator Network Paging Protocol). For terminals transmitting POCSAG formatted selective call information, though, certain seven-bit ASCII control characters are not permitted in selective call message fields. Thus, some ASCII seven-bit patterns are not transmittable, even though the patterns may be integral to the selective call message.
Thus, what is needed is a method and apparatus for handling information received in multiple data formats and presenting the information to a selective call terminal in known signalling formats.